1. Field of the Invention
The present invention relates to an image forming apparatus, such as a color printer or a color copier. More particularly, the present invention relates to an image forming process module in which a photoreceptor unit and a development unit are integrated, and an image forming apparatus having the same.
2. Description of the Related Art
Referring to FIG. 1, a conventional image forming apparatus 10, such as a color printer or a color copier, includes a photoreceptor 11 configured like a drum and is continuously rotated in one direction, such as clockwise, by a photoreceptor driving motor (not shown).
Around the circumferential outer edge of the photoreceptor 11, an electrification unit 12, a laser scanning unit (LSU) 20, a development unit 30, an image transfer unit 60, a charge-removing lamp 87 and a cleaning and charge-removing unit 80 are disposed in order in the direction of rotation of the photoreceptor 1.
The electrification unit 12 includes a scorotoron electrifier and electrifies the photoreceptor 11 uniformly. The LSU 20 exposes the photoreceptor 11 to a light source, such as a laser diode, to form a latent image.
The development unit 30 includes four development assemblies 31, 32, 33 and 34 having yellow (Y), magenta (M), cyan (C) and black (K) developers, respectively, therein.
Each of the development assemblies 31, 32, 33 and 34 includes a developer storage part 16, a development roller 13, a developer supply roller 15 and a blade 51 serving as a developer layer limitation member for limiting the thickness of a developer layer attached on the developer roller 13. Such components constituting each development assembly are integrated into a single body so that each of the development assemblies 31, 32, 33 and 34 is replaced with a new one as a whole when the lifespan of any component of each development assembly 31, 32, 33 and 34 is ended. The developments assemblies 31, 32, 33 and 34 are installed into a main frame or a fixing frame (not shown) of a main body of an image forming apparatus.
The developer storage part 16 is structured to be sealed so that a new developer cannot be refilled. Alternatively, the developer storage part 16 can be structured to have a detachable developer cartridge so that a developer can be refilled when the developer in the developer storage part 16 is depleted simply by replacing the old developer cartridge with a new one. The developer stored in the developer storage part 16 is supplied to the development roller 13 by the developer supply roller 15 of the development storage part 16, which is supplied with a bias voltage. Furthermore, the thickness of the developer on the development roller 13 is limited by the blade 51, which applies a predetermined charge injection voltage to the developer on the development roller 13.
The development roller 13 and the developer supply roller 15 are driven to rotate by a development unit gear train (not shown) connected to a photoreceptor drive motor.
In each development assembly 31, 32, 33 and 34, a development bias voltage supply unit is provided between the development roller 13 and a high voltage power source (not shown). The development bias voltage supply unit changes a voltage supplied from the high voltage power source to a predetermined development bias voltage and supplies the development bias voltage to the development assemblies 31, 32, 33 and 34 in turns.
The image transfer unit 60 elastically transfers a color developer image formed in the photoreceptor 11 onto an image reception medium P, such as a record paper. The cleaning and charge removing unit 80 removes the developer remaining in the photoreceptor 11.
The conventional image forming apparatus 10 has the following disadvantages.
First, because the conventional image forming apparatus 10 stated above is structured to have the photoreceptor 11 and the development assemblies 31, 32, 33 and 34 of the development unit 30 that are realized as separate components, it requires significant time and labor to manufacture the image forming apparatus or to replace components thereof, resulting in low assembly and replacement efficiency.
Second, because the conventional image forming apparatus 10 stated above is structured to have the photoreceptor 11 and the development assemblies 31, 32, 33 and 34 of the development unit 30 that are realized as separate components, sizes of the components should be severely designed and managed to make each component precisely organized and smoothly detached. Accordingly, it is difficult to manufacture the image forming apparatus.
Third, when the developer storage part 16 is structured to be sealed to not be refilled with a new developer, the development assemblies 31, 32, 33 and 34 should be designed to have a large size to increase replacement periods of the development assemblies 31, 32, 33 and 34 of the development unit 30. Accordingly, the development unit 30 has a large size and it is difficult to realize an image forming apparatus 10 having a compact size.
Accordingly, a need exists for an image forming apparatus having an integrated photoreceptor unit and development unit.